<!DOCTYPE html>
<html>
<head>
<title>Layer Bands using a Background Part</title>
<meta name="description" content="Showing bands for the layers in a diagram." />
<!-- Copyright 1998-2016 by Northwoods Software Corporation. -->
<meta charset="UTF-8">
<script src="go.js"></script>
<link href="../assets/css/goSamples.css" rel="stylesheet" type="text/css" />  <!-- you don't need to use this -->
<script src="goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
<script id="code">

  // this controls whether the layout is horizontal and the layer bands are vertical, or vice-versa:
  var HORIZONTAL = true;  // this constant parameter can only be set here, not dynamically

  // Perform a TreeLayout where commitLayers is overridden to modify the background Part whose key is "_BANDS".
  function LayeredTreeLayout() {
    go.TreeLayout.call(this);
    this.layerStyle = go.TreeLayout.LayerUniform;  // needed for straight layers
  }
  go.Diagram.inherit(LayeredTreeLayout, go.TreeLayout);

  /** @override */
  LayeredTreeLayout.prototype.commitLayers = function(layerRects, offset) {
    // update the background object holding the visual "bands"
    var bands = this.diagram.findPartForKey("_BANDS");
    if (bands) {
      var model = this.diagram.model;
      bands.location = this.arrangementOrigin.copy().add(offset);

      // make each band visible or not, depending on whether there is a layer for it
      for (var it = bands.elements; it.next(); ) {
        var idx = it.key;
        var elt = it.value;  // the item panel representing a band
        elt.visible = idx < layerRects.length;
      }

      // set the bounds of each band via data binding of the "bounds" property
      var arr = bands.data.itemArray;
      for (var i = 0; i < layerRects.length; i++) {
        var itemdata = arr[i];
        if (itemdata) {
          model.setDataProperty(itemdata, "bounds", layerRects[i]);
        }
      }
    }
  };
  // end LayeredTreeLayout


  function init() {
    if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
    var $ = go.GraphObject.make;

    myDiagram = $(go.Diagram, "myDiagramDiv",
                  {
                    initialContentAlignment: go.Spot.Center,
                    layout: $(LayeredTreeLayout,  // custom layout is defined above
                              {
                                angle: HORIZONTAL ? 0 : 90,
                                arrangement: HORIZONTAL ? go.TreeLayout.ArrangementVertical : go.TreeLayout.ArrangementHorizontal
                              }),
                    "undoManager.isEnabled": true
                  });

    myDiagram.nodeTemplate =
      $(go.Node, go.Panel.Auto,
        $(go.Shape, "Rectangle",
          { fill: "white" }),
        $(go.TextBlock, { margin: 5 },
          new go.Binding("text", "key")));

    // There should be at most a single object of this category.
    // This Part will be modified by LayeredTreeLayout.commitLayers to display visual "bands"
    // where each "layer" is a layer of the tree.
    // This template is parameterized at load time by the HORIZONTAL parameter.
    // You also have the option of showing rectangles for the layer bands or
    // of showing separator lines between the layers, but not both at the same time,
    // by commenting in/out the indicated code.
    myDiagram.nodeTemplateMap.add("Bands",
      $(go.Part, "Position",
        new go.Binding("itemArray"),
        {
          isLayoutPositioned: false,  // but still in document bounds
          locationSpot: new go.Spot(0, 0, HORIZONTAL ? 0 : 16, HORIZONTAL ? 16 : 0),  // account for header height
          layerName: "Background",
          pickable: false,
          selectable: false,
          itemTemplate:
            $(go.Panel, HORIZONTAL ? "Vertical" : "Horizontal",
              new go.Binding("position", "bounds", function(b) { return b.position; }),
              $(go.TextBlock,
                {
                  angle: HORIZONTAL ? 0 : 270,
                  textAlign: "center",
                  wrap: go.TextBlock.None,
                  font: "bold 11pt sans-serif",
                  background: $(go.Brush, "Linear", { 0: "aqua", 1: "whitesmoke" })
                },
                new go.Binding("text"),
                // always bind "width" because the angle does the rotation
                new go.Binding("width", "bounds", function(r) { return HORIZONTAL ? r.width : r.height; })
              ),
              // option 1: rectangular bands:
              $(go.Shape,
                { stroke: null, strokeWidth: 0 },
                new go.Binding("desiredSize", "bounds", function(r) { return r.size; }),
                new go.Binding("fill", "itemIndex", function(i) { return i % 2 == 0 ? "whitesmoke" : "aquamarine"; }).ofObject())
              // option 2: separator lines:
              //(HORIZONTAL
              //  ? $(go.Shape, "LineV",
              //      { stroke: "gray", alignment: go.Spot.TopLeft, width: 1 },
              //      new go.Binding("height", "bounds", function(r) { return r.height; }),
              //      new go.Binding("visible", "itemIndex", function(i) { return i > 0; }).ofObject())
              //  : $(go.Shape, "LineH",
              //      { stroke: "gray", alignment: go.Spot.TopLeft, height: 1 },
              //      new go.Binding("width", "bounds", function(r) { return r.width; }),
              //      new go.Binding("visible", "itemIndex", function(i) { return i > 0; }).ofObject())
              //)
            )
        }
      ));

    myDiagram.linkTemplate =
      $(go.Link,
        $(go.Shape));  // simple black line, no arrowhead needed

    // define the tree node data
    var nodearray = [
      { // this is the information needed for the headers of the bands
        key: "_BANDS",
        category: "Bands",
        itemArray: [
          { text: "Zero" },
          { text: "One" },
          { text: "Two" },
          { text: "Three" },
          { text: "Four" },
          { text: "Five" }
        ]
      },
      // these are the regular nodes in the TreeModel
      { key: "root" },
      { key: "oneB", parent: "root" },
      { key: "twoA", parent: "oneB" },
      { key: "twoC", parent: "root" },
      { key: "threeC", parent: "twoC" },
      { key: "threeD", parent: "twoC" },
      { key: "fourB", parent: "threeD" },
      { key: "fourC", parent: "twoC" },
      { key: "fourD", parent: "fourB" },
      { key: "twoD", parent: "root" }
    ];

    myDiagram.model = new go.TreeModel(nodearray);
  }
</script>
</head>
<body onload="init()">
<div id="sample">
  <h3>GoJS Layer Bands</h3>
  <div id="myDiagramDiv" style="border: solid 1px blue; width:100%; height:600px;"></div>
  <p>
    Unlike swim lane diagrams where the nodes are supposed to stay in their lanes,
    layer bands run perpendicular to the growth direction of the layout.
  </p>
  <p>
    This sample uses a custom <a>TreeLayout</a> that overrides the <a>TreeLayout.commitLayers</a> method
    in order to specify the position and size of each "band" that surrounds a layer of the tree.
    The "bands" are held in a single Part that is bound to a particular node data object whose key is "_BANDS".
    The headers, and potentially any other information that you might want to display in the headers,
    are stored in this "_BANDS" object in an Array.
  </p>
  <p>
    This sample can be adapted to use a <a>GraphLinksModel</a> instead of a <a>TreeModel</a>
    and a <a>LayeredDigraphLayout</a> instead of a <a>TreeLayout</a>.
  </p>
</div>
</body>
</html>